1. Field of the Invention
The present invention provides an improved air cleaner, or filter, for internal combustion engines and particularly adapted for use with motorcycles, the filter having a conical frustum shape configured with foam materials in multiple layers.
2. Description of the Prior Art
Air filters designed for use with internal combustion engines have been available for many years. The air cleaner is typically installed in an air-cleaner case mounted beneath the seat and is connected to carburetor through the intake pipe.
Conventional air cleaners for off-road motorcycles are typically shaped as a conical frustum having a cavity opening at its inner section. The prior art air cleaner is typically made in a wet sponge format, i.e. foam sponge is immersed in viscous oil and then used with the air cleaner. In order to prevent reduced air flow due to dust deposits, the wet sponge filters utilize a double-layered structure wherein a coarse sponge is placed on the air cleaner outer layer and a covering a fine sponge placed as the inner layer. The sponges typically are the same thickness.
It is known that air cleaners are essential to protect the engine from dirt and sand in order to ensure its durability; engines having low ventilation resistance are considered desirable because air flow injected into the engine creates resistance. Current air filters result from a comprise between the ability to block dirt and sand and injected air resistance, air flowing evenly from many directions at the same time. In this regard, and referring to FIGS. 7-9, prior art air cleaner 50 utilizes different sponges 51 and 52 for its outer and inner layers, each sponge being made of the same material and of the same thickness for the entire surface area. This allows the same amount of air to flow into the air cleaner 50 from all surface areas. That in turn causes the air 51 flowing from the side-surface section to collide with the air 52 flowing from the upper surface section on the inside of the air cleaner 50 causing air turbulence. As a result the air intake to the engine decreases, decreasing engine efficiency.
U.S. Pat. No. 4,039,308 to Schiff discloses a device formed of rigid foam material which functions both to filter and straighten air introduced thereto prior to being directed to the vehicle air intake. Specifically, the device comprises an integral air filter and air straightening means made of the same porous material. The air straightening means performs two functions, i.e. that of cleaning air introduced thereto in a manner similar to that accomplished by an air cleaner while also reducing the turbulence of the cleaned air before being introduced to an air intake device, such as a carburetor.
Although the air cleaners disclosed in the prior art, such as illustrated in the '308 patent, provide an increased flow of cleaned air at the air intake of the internal combustion engine, the air flow comprises two components having two different velocity vectors; the resultant mixed air flow reducing the total amount of useful air flow to the air intake, thus reducing engine efficiency.
What is desired is to provide a simple, yet cost efficient, light weight air cleaner that creates increased air flow into the engine, thus increasing engine efficiency.